Known as a data recording/reproducing apparatus able to record a great amount of data is a holographic recording/reproducing apparatus, for example. The holographic recording/reproducing apparatus includes a holographic storage medium used as data recording medium. On the inside of the holographic storage medium, a signal beam superimposed with data to be recorded interferes with a reference beam, thereby forming interference fringes. The interference fringes (hologram) are recorded, as data, on the holographic storage medium.
In such a data recording/reproducing apparatus, the address data recorded on the data recording medium is reproduced when data is recorded or reproduced on or from the recording medium. The light-beam applying position is controlled in accordance with the address data so that the light beams may be applied at the target position on the data recording medium.
Therefore, it is necessary to reproduce, at high accuracy, the address data recorded on the data recording medium to control the light-beam irradiating position.